EP 2 216 834 Al describes an optoelectronic semiconductor device.
Some devices comprise a lead frame having a suitable plastic material injection-molded around it. The plastic material forms a basic housing comprising a cavity in which a semiconductor chip is arranged and electrically contacted. To increase the external efficiency in such devices, it is conventional to form the cavity with inclined inner surfaces so that they serve as a reflector. The semiconductor chip in the cavity mostly emits radiation directed forwardly, sidewardly and rearwardly. In those devices, in spite of the inclined cavity inner surfaces sideward- or rearward-emitted light of the semiconductor chip is absorbed at least partially by the basic housing, which means that the light portion disadvantageously does not contribute to the forward light current of the device.
Moreover, in some devices, absorption losses of the radiation emitted by the semiconductor chip can occur on absorbing contact structures arranged, e.g., at a radiation passage side of the semiconductor chip. Moreover, by reason of the properties of the semiconductor chip as a volume emitter, efficient coupling of light into optical elements such as, e.g., into waveguides, cannot easily be accomplished using such devices.
To counteract those disadvantages at least in part, it is possible to use a housing material which is preferably reflective. However, some reflective housing materials have for the most part disadvantageous properties such as, e.g., low thermal conductivity. Alternatively or in addition, it is possible to use large-area contact surfaces consisting of, e.g., silver to recover light emitted in the rearward direction. However, shadowing effects can occur which means that an optimum forward light current also cannot be achieved.
Thus, there is a need to provide an optoelectronic semiconductor device characterized by an increased forward light current and at the same time permits efficient coupling of light into optical elements, wherein the device can also be produced having just a small height.